Treatment of lubricant stocks



Patented Apr. 3, 1928.

. UNITED STATES v 1,665,111 PATENT OFFICE.

GEORGE FREDRIC OLSEN, 01F LOS ANGELES, CALIFORNIA, ASSIGNOR TO GENERAL PETROLEUM CORPORATION OF CALIFORNIA, OF LOS ANGELES, CALIFORNIA, A COR- PORATION OF DELAWARE.

TREATMENT OF LUBRICANT STOCKS.

I No Drawing.

My invention relates to the treatment of petroleum oil stocks consisting essentially of lubricants with liquefied sulfur dioxid.

The object of my invention is to so govern the course of the sulfur dioxid extraction as to obtain, from such viscous stocks, an extractive having such physical properties that it may be completely and readily removed from the remainder of the extracted oil.

The general and commonly used manner of treating petroleum distillates with sulfur dioxid is well known and understood.

, It consists, first, in liquefying gaseous sulfur dioxid by pressure and coo-ling; second, in intermixing the heavy liquid thus produced with an oil to be treated, a portion of the oil passing into solution with the sulfur dioxid while another portion remains undissolved; third, in parting the bottom or solution layer from the upper or undissolved layer; fourth, in removing any entrained sulfur dioxid from the upper layer; fifth, in distilling out of the lower layer the bulk of the sulfur dioxidwhich is then condensed as before to enter a new cycle.

In the conduct of this process, no matter what the nature of the raw material, two fractions are obtained. The upper or undissolved layer consists of bodies rich in hydrogen-saturated aliphatic hydrocarboils-purified to a-high degree and well These bodies have their uses, but in-admix- 'ture with the saturated aliphatics they are simply impurities, and the object of the treatment is to remove them for thepurification of the undissolved layer.

The separation of the upper layer from ,the lower :layer must be complete in both directions if satisfactory results are to be obtained. That is to say, not only must the lower layer settle completely out of the Application filed October 15, 1927. Serial No. 226,507.

be found to be materially heavier and more viscous than the upper, and there is usually little difficulty in cleanly parting the lower layer from the upper, but even with light oils there is often some difliculty in prevent ing entrainment of portions of the upper layer in the lower. In the case of lubricating oils, which at the low temperatures prevailing inthis process are extremely viscous, it is often impossible to obtain a clean separation in either direction, so that the upper layer is seriouslycontaminated with the unstable unsaturated products which it is desired to remove, while the relatively valueless lower layer will entrain a serious proportion of the valuable upper layer. In extreme cases the two layers will emulsify, and no separation whatever take place.

In order toavoid this difiiculty and to make it possible to use this method to full advantage even on the heaviest lubricating oils, I make use of two steps not heretofore proposed, which steps may beused independently if desired, but are preferably used in combination.

upper layer. Whether a raw or a previous- 'ly treated solvent should be used is a matter of policy only. If a raw solvent be used it will be subjected to the treatment along with the lubricating oil, and when removed from the purified layer as hereinafter described will be recovered as a purified material suitable for its proper use. On the other hand, it may be more convenient as enabling the operator to better control his dosage of sulfur dioxid,'to cycle the purified solvent through a series of treatments. I do not limit my invention to either purified or unpurified solvent, nor to either gasoline: or' kerosene, either of which may be A. P. I. gravity. This proportion will obvi ously depend on the gravity and theviscosity of the stock to be treated. I prefer to use such quantity of solvent as will bring the gravity up to at least A. P. I. and

the vicosity down to about 80 seconds at 100 F. Saybolt universal, but good results may be had by using materially less proportions of solvent, and I do not limit my invention to any specific proportion thereof.

The second step in my invention, which as said may be used in connection with the firststep or independently thereof, consists in adding either to the oil tobe treated or to the above said solution thereof, a mate rialproportion of an extractive (recovered from the lower layer) from a previous treatment of gasoline or kerosene. As might be expected, it is a fact that the extractive from a gasoline is lighter and less viscous than the extractive from a kerosene, and so on down the scale until the extractive from a very heavy lubricant is so viscous as to be practically solid. By theaddition of a light and nonviscous extractive. to a viscous oil to be treated, the extractive from the viscous oil is diluted by the non-viscous extractive to such extent that entrainment of portions of the upper layer in the body of the lower layer may be entirely prevented and a perfectly clean separation may be obtained.

It isimpossible to state .any proportion of light extractive to be used, as this proportion will vary widely,-not only witlr the viscosity of the light extractive itself, but also and to a, much greater extent with the natural viscosity of the extractive from the oil to, be treated. In some cases, as in the treatment of relatively low viscosity distillates, a small proportion of light extractive will be suflicient to render the lower layer sufliciently fluid to handle; in others, as for instance heavy distillates or residua from asphaltic oils, a quite large proportion may be required. I therefore do not limit myself to any specific proportion of light extractive, and when I refer to a suficient proportion of light extractive in this specifica tion or theattached claims, I would be,understood as meaningsuch quantity of an extractive obtained from a light petroleum product of the general nature of gasoline or kerosene as will dilute theextractive from the oil to be treated to a point where it will cease to entrain material proportions of the upper layer and at which a clean separation of the layers may be effected. In any specific case this proportion must be found by trial, bearing in mind that the sole purpose of the addition of the light extractive is to lower the viscosity of the heavy or viscous extractive from the oil to be treated.

In the conduct of my invention no apparatus is required other than that in common use for the treatment of petroleum oils with liquefied sulfur dioxid and for the fractionation of petroleum products, nor is any special or unusual manipulation of the treatment process itself called for, my invention residing in the steps above set forth, which are interposed in the usual treatment in their appropriate place. The following description applies'to the use of both steps, but

will apply equally to the application of either step Without the other.

Having selected a lubricant stock to be.

treated, I firstdilute it with a solvent as above described, using by preference a quanity suificient to bring the A. P. I. gravity up to not less than 30 or the Saybolt viscosity at 100 F. down to not over'80 sec onds. If the second step also is to be applied, I add to the above solution (or to the oil itself in case the first step is to be omitted) a sufiicient quantity of a light extractive. In any case the ingredients are thoroughly and carefully intermixed.

I then proceed to the extraction with liquefied sulfur dioxid in the usual and well known manner, mixing for the usual time and allowing the mixture to form two layers by gravitation. If the proper proportions of solvent and of light extractive have been used the'separation will be rapid and complete. The lower layer is: then withdrawn and the sulfur dioxid distilled out in the usual manner, after JWhlCh the mixture of extractives is fractionally distilled in any usual or preferred manner, the light frac- 1 tion being recovered for reuse in a succeed ing batch while the heavy fraction is put to such use as may be preferred, this heavy fraction being identical with that which would have been obtained had the light extractive not been added, with the exception that. it will be free fromL-any portions ofthe material composing the upper layer.

Theupper layer is then withdrawn from the extraction apparatus and'freed from adhering traces of sulfur dioxid in the usual manner, and thereafter or concurrently separated from the solvent by fractional distillation in any usual or preferred manner, the

solvent being recovered as a purified gasoline or kerosene, as the case may be, for use as such or for recycling, while the lubricating residue will be found to be entirely free from bodies soluble in sulfur dioxid and thoroughly purified.

Whilethe above described steps applied in the said treatment produce highly useful and valuable results, they are admittedly open to the objection that an increased dose ofsulfur dioxid is required to dissolve the light extractive added to the heavy oil. Under certain circumstances, as for instance where-a relatively large proportion of gasoline and a relatively small proportion of lubricating oil are to be treated, the above process may be modified without in the least departing from the spirit of my invention, by simultaneously treating a gasoline or kerosene and a lubricating oil, neither of which have previously been treated in this maner. If, for instance, three parts of a kerosene rich in extractives, such as California kerosene, be mixed with one part of a viscous lubricant and. the mixture treated with sulfur dioxid in the usual manner, the result will be a separation into two fractions, one containing a mixture of kerosene and lubricating oil, both thoroughly purified, and a mixture of light and heavy extractives. Proceeding in this manner both the lubricating oil and the heavy extractive will be sufliciently diluted to obtain quick and clean separation of the layers. The mixture of kerosene (or'gasoline, if preferred) and lubricating oil may then be submitted to fractional distillation, and the mixture of extractives may also be so separated if the use to which they are to be put requires such separation. No more sulfur dioxid will be required than in the separate treatment of the two oils, in fact the consumption will usually be less on account of the reduced viscosity of the heavy extractive. The only limitation to this method of applying my invention lies in the necessity of using materials having such boiling ranges that they will not overlap'and cause mutual contamination in the fractionation of the extracted oil.

I am well aware that the treatment of petroleum products with liquefied sulfur dioxid has heretofore been known and used, and

light petroleum product, such portion of said viscous oil as is soluble in said sulfur (lioxid.

2. In the fractionation and purification of viscous petroleum oils by treatment with liquid sulfur dioxid, the steps comprising: diluting said viscous oil with a light petroleum solvent and adding to said diluted oil a sufficient quantity of a light petroleum extractive obtained from a light petroleum product.

3. In the fractionation and purification of viscous petroleum oils by treatment.with liquid sulfur dioxid, the steps comprising: adding to said viscous oil asufficient quantity of a light extractive previously obtained from a light petroleum product and a solvent consisting of a light petroleum product.

t. As a step in the fractionation and purification of viscous petroleum oils by treatment with liquid sulfur dioxid: adding to said viscous oil, prior to said treatment, a sufiicient quantity of a light extractive derived from a less viscous petroleum oil.

5. As step in the simultaneous fractionation and purification of viscous petroleum oils and non-viscous petroleum oils by treatment with liquid sulfur dioxid: mixing with said viscous oil, prior to said treatment, such proportion of said non-viscous oil as will yield. under said treatment, a suflicient quantity of light extractive to materially reduce the viscosity of the heavy extractive simultaneously separated from said viscous oil by said treatment.

In witness that I claim the foregoing I have hereunto subscribed my name this 6th day of October, 1927.

GEORGE FREDRIC OLSEN. 

